1. Field of the Invention
The present invention relates to a digital/analogue TV (television) receiver having an EPG (electric program guide) screen display function, by which electric information of TV programs delivered within TV broadcasting signals are extracted and the EPG screen including TV program guide such as channels and contents of the TV programs are displayed.
2. Description of the Related Art
In recent years, digital TV broadcast is quickly popularized owing to progression of digital technology. In the digital TV broadcast, a plurality of TV programs is delivered in a single frequency band. Image signals and sound signals of the TV programs are encoded by compression owing to digital data compression technology, and the encoded signals are time shared and multiplexed. Subsequently, the time shared and multiplexed signals are modulated to high frequency radio waves in a predetermined frequency band, and delivered as the TV broadcasting signals. In the digital TV broadcast, the electric information of the TV programs including the channel information of the TV programs are delivered with the image signals and the sound signals of the TV programs at a predetermined interval by time sharing and multiplexing them.
In the digital TV broadcast, the TV broadcasting signals in the predetermined frequency band, which is formed by time sharing and multiplexing a plurality of TV broadcasting signals of the TV programs, is called “physical channel”, and each TV broadcasting signal of the TV program, which is to be multiplexed in the frequency band, is called “sub-channel”.
In a TV receiver for receiving the digital TV broadcasting signals, when a user selects a channel (physical channel and sub-channel) of a TV program which he wishes to see by operating a channel changer, the high frequency radio waves in the predetermined frequency band corresponding to the physical channel are received. By decoding the received radio waves, a signal called “transport stream signal” can be obtained, in which the encoded image signals and sound signals of the TV programs and the electric information of the TV programs are time shared and multiplexed.
The TV receiver extracts and separates the image signal and the sound signal of the TV program corresponding to the sub-channel from the transport stream signal. Subsequently, the TV receiver decodes the image signal and the sound signal to the states of them before the compression, and outputs the decoded image signal and sound signal to a display apparatus. The TV receiver further has a function to extract the electric information of the TV programs from the transport stream signal, to form the electric program guide (EPG) consisting of titles, channels, broadcast times and so on of the TV programs, and to display the EPG screen on the display apparatus. The displaying of the EPG screen on the display apparatus is selected by operating the channel changer.
In North America, the digital TV broadcast called ATSC (advanced television system committee) is delivered. The ATSC broadcast delivers information called PSIP (program and system information protocol) including various data with respect to the TV broadcast multiplexed with the image signals and the sound signals of the TV programs on air in each physical channel. The PSIP further includes electric information of TV programs called VCT (virtual cannel table) and EIT (event information table).
The VCT relates to information showing a relation between a cannel number and a source ID of a TV program on air, which includes channel number information and a source ID corresponding to a sub-channel of the TV program on air. The EIT relates to information showing a relation between TV program information and a source ID of a TV program on air or scheduled, which includes TV program information such as a title, start and end times of the TV program and the source ID.
In the conventional TV receiver for receiving the ATSC broadcast, when the user selects to display the EPG screen by operating the channel changer, an EPG screen 70, for example, shown in FIG. 9 is displayed on the display apparatus. On the EPG screen 70, a plurality of channel grids 71 shows channel numbers of the TV programs, and a plurality of program grids 72 disposed at right side of the channel grids 71 shows titles of the TV programs which will be come on the air on the channel. Start times of the TV programs are shown above the program grids 72. On the EPG screen 70, the TV programs are shown correspondingly to the channels and the start times.
The EPG screen 70 can be scrolled above and below by operating the channel changer so as to show other channels. In FIG. 9, the channel grids 71 corresponds to the channels 34-1 to 50-2. When any one of the channel grids 71 is selected by operating the channel changer, the TV broadcasting signals corresponding to the selected channel is tuned, so that an image of a TV program on the channel is appeared on the display apparatus. When an EXIT grid 76 of the EPG screen 70 is selected, the EPG screen is disappeared.
For showing the RPG screen 70, it is necessary that the titles and the start times of the TV programs are corresponded to the channels. As mentioned above, the EIT includes the TV program information such as the title and the start and end times of the TV program and the source ID, but includes no channel number information. On the other hand, the VCT includes the channel number information and the source ID corresponding to the TV program, but includes no TV program information such as the title and the start and end times. Thus, the correspondence of the title and the start time of the TV program with the channel is based on the source ID commonly included in the EIT and the VCT.
A conventional apparatus, for example, shown in Publication Gazette of Japanese Patent Application 2001-86425 takes a table including the channel number information and a table including event information, and supplies a channel list corresponding to the time of the events to the users, with respect to displaying the TV program information of the digital TV broadcast. Another apparatus, for example, shown in Publication Gazette of Japanese Patent Application 2001-136495 can display the information of local events in the EPG of the digital TV broadcast in detail, and can store and transmit the program data.
In the above-mentioned conventional TV receivers, the TV broadcasting signals of all the physical cannels are serially tuned and received, after the operation for displaying the EPG screen. Subsequently, the VCTs and the EITs are extracted from the TV broadcasting signals of each physical channel, and the titles and the start times of the TV programs are corresponded to the channels with using the source IDs commonly included in the EITs and the VCTs. Therefore, it takes a long time after operating the EPG screen displaying for forming and displaying the completed EPG screen on which the TV program information with respect to all of the physical channels are shown.
Furthermore, when the operation for displaying the EPG screen is started, another operation such as for selecting the TV channel cannot be operated until the EPG screen is displayed. Thus, the user has no alternative but to wait until the EPG screen is displayed, so that the user feels annoyance or discomfort. Such the disadvantage cannot be solved even when the technologies shown in the above-mentioned publication gazettes are applied.